1. Field of the Invention
The present invention relates generally to a portable wireless device such as a portable phone, a cellular phone, a transceiver, a wireless receiver, or a wireless transmitter. More particularly, the present invention relates to a portable wireless device made up of a first housing with a user interface mounted therein facing forward, a second housing hingedly connected to the first housing and holding an antenna support, and an antenna unit telescopically received in the antenna support.
2. Description of the Prior Art
FIG. 1 shows the front view of a conventional portable phone. An example of such portable phone is described in Japanese Patent Laid-Open Gazette No. 259726/93. Reference number 122 denotes a helical antenna, 123 denotes an antenna cover, 124 denotes an antenna fixture, and 125 denotes a housing. The housing 125 has a user interface such as a loudspeaker and a microphone built therein.
Such a portable phone includes internal circuits (not shown) for performing various processing in response to user input, thereby sending and receiving radio wave signals via the antenna (the helical antenna 122).
Normally a user holds the housing 125 close to his head while using the portable phone. Accordingly, the user""s head becomes an obstacle to antenna transmission and/or reception. The transmission and/or reception signal characteristics of the portable phone are degraded as compared with those obtainable when the antenna is placed in free space. An example of signal degradation is reported in xe2x80x9cMeasurements of the Radiation Efficiency of an Antenna Placed near COST 244 Prescriptive Model,xe2x80x9d in Proc. IEICE Communication Society Meeting, pp.103, September 1998. FIG. 2 depicts the positional relationship between a model to simulate a human head and an antenna in a measuring system used in the report. FIG. 3 shows the measurement results obtained by using the measuring system and the calculation results obtained by using Finite-Difference Time-Domain (FDTD) method. Specifically, measurement and calculation results using both cubic and spherical models as human head are shown in FIG. 3. The report (FIG. 3) reveals that the radiation efficiency decreases dramatically when the human body model and the antenna are spaced less than about three centimeters apart.
When the radio wave conditions are not good owing to such a characteristics deterioration, poor communications are likely to occur.
FIG. 4 depicts a perspective view of another conventional portable phone. It is based on the portable phone described in International Publication WO97/26714. FIG. 5 is a plan view of the portable phone showing its flip-up cover. Reference number 201 denotes the case of the portable phone; 202 denotes a flip-up cover which is mounted on the top of the case 201 in a manner to be pivotable about two axes. The flip-up cover is used to cover an operating panel of the portable phone while the phone is not in use; 211 and 212 denote patch antennas built in the flip-up cover 202. The patch antennas 211 and 212 are mounted on the cover 202 as close to its far end edge 221 as possible so that they are held as far apart as possible from the user while in use. The flip-up cover 202 is suitably turned by the user about the two axes to adjust the orientation of the patch antennas 211 and 212 for better transmission and reception of signals as electric waves.
The above traditional portable phone has a problem that the patch antenna 212 cannot be held at a sufficient distance from the user""s head because of the limited length of the flip-up cover 202. While the patch antennas 211 and 212 can be easily built in the flip-up cover 202 because of their flat configuration, the use of a rodlike antenna gives rise to another problem of the prior art which is the difficulty in its incorporation in the flip-up cover 202.
It is therefore an object of the present invention to provide a portable wireless device in which a first housing with communicating means mounted therein facing forward and a second housing supporting a telescopic antenna unit are pivotally interconnected so that the distance between the antenna and the user can be long enough to suppress the deterioration of the transmission and/or reception signal characteristics while in use.
According to an aspect of the present invention, there is provided a portable wireless device which comprises: a first housing with communicating means built therein facing forward; a second housing holding an antenna support along one side thereof; an antenna unit telescopically received in the antenna support; and hinge connections hingedly connecting the second housing to the back of the first housing about an axis in the lengthwise direction thereof. With this structure, it is possible to increase the distance between the user""s head and the antenna unit while in use and to keep the antenna unit from being inadvertently touched by the user""s hand holding the first housing, thereby preventing the deterioration of the transmission and/or reception signal characteristics. Because of its telescopic structure, the antenna unit can be extended longer than the length of the first housing, thus achieving improved transmission and/or reception signal characteristics. While not in use, the antenna unit can be retracted back into the antenna support. This allows for increased portability of the portable wireless device.
According to another aspect of the present invention, the portable wireless device has a sleeve-dipole antenna in the antenna unit. This further increases the distance between the user""s head and the antenna while in use, further preventing the deterioration of the transmission and/or reception signal characteristics.
According to another aspect of the present invention, the portable wireless device has a sleeve-dipole antenna provided with a helical radiation part. This antenna structure permits miniaturization of the sleeve-dipole antenna, increasing its distance from the user""s head while in use and thus further preventing the transmission and/or reception signal characteristics from degradation. The miniaturization of the sleeve-dipole antenna allows miniaturization of the antenna support as well.
According to another aspect of the present invention, the portable wireless device has a four-wire helical antenna in the antenna unit. This antenna structure sufficiently increases the distance between the user""s head and the antenna while in use, further preventing the degradation of the transmission and/or reception signal characteristics.
According to another aspect of the present invention, there is provided a portable wireless device which comprises: a first housing with communicating means mounted therein facing forward; a second housing holding an antenna support along one side thereof; an antenna unit telescopically received in the antenna support; and hinge connections hingedly connecting the second housing to the back of the first housing about an axis widthwise thereof. With this structure, it is possible to increase the distance between the user""s head and the antenna while the portable wireless device is in use and to keep the antenna from being easily touched by the user""s hand holding the first housing, thereby preventing the deterioration of the transmission and/or reception signal characteristics. Because of its telescopic structure, the antenna unit can be extended longer than the width of the first housing, thus achieving improved transmission and/or reception signal characteristics. While not in use, the antenna unit can be retracted back into the antenna support. This provides increased portability of the portable wireless device. While the portable wireless device is in use, the first housing is normally held substantially horizontal with the antenna unit pointing virtually in the vertical direction. Consequently, vertically polarized waves can be received with low loss. Furthermore, the transmission and/or reception signal characteristics can be improved for communications which require a coverage about the zenith.
According to another aspect of the present invention, the portable wireless device has a sleeve-dipole antenna in the antenna unit. This further increases the distance between the user""s head and the antenna while in use, further preventing the deterioration of the transmission and/or reception signal characteristics.
According to another aspect of the present invention, the portable wireless device has a sleeve-dipole antenna provided with a helical radiation part. This antenna structure permits miniaturization of the sleeve-dipole antenna, increasing its distance from the user""s head while in use and hence further preventing the transmission and/or reception signal characteristics from degrading. The miniaturization of the sleeve-dipole antenna allows miniaturization of the antenna support as well.
According to still another aspect of the present invention, the portable wireless device has a four-wire helical antenna in the antenna unit. This antenna structure sufficiently increases the distance between the user""s head and the antenna while in use, further preventing the degradation of the transmission and/or reception signal characteristics.